<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style></style>
    
    <!-- 2.内嵌式的js，与css写法相似 -->
    <script>
        // alert('寅子牛逼');
    </script>

    <!-- 3.外部的js写法，注意是双标签 -->
    <!-- 注意这两个<script></script>的标签中间不要再写代码 -->
    <script src="my.js"></script>
</head>

<body>
<!-- 1.行内式的js，直接写到元素的内部-->
<!-- <input type="button" value="唐伯虎" onclick="alert('秋香姐')"> -->
</body>

</html>